1. Field of the Invention:
This invention relates to an improved control system for car washing apparatus, and in particular for car washing apparatus which washes automatically the front, side and rear of a car as such car passes thereby.
2. Description of the Prior Art
In U.S. Pat. No. 3,624,851, issued Dec. 7, 1971 to Ivan J. Barber, there is shown car washing apparatus having a primary arm pivotally supported on one end at one side of the path of the car and extending rearwardly along such path, a secondary arm pivotally supported at one end from the free end of the primary arm and normally extending approximately transversely over the path of the car, and a brush rotatably mounted on the free end of the secondary arm. As the car moves into contact with the brush, and pushes the secondary arm forwardly relative to the primary arm, a position switch operates and causes actuation of a primary arm piston and cylinder which retracts the primary arm. This draws the brush across the front of the car and the car movement folds the secondary arm relative to the primary arm. When the brush passes around the front corner of the car, a bias pressure begins to unfold the secondary arm relative to the primary arm. This unfolding movement triggers a pressure operated valve, which reverses the primary arm piston and cylinder, causing the primary arm to move outwardly, maintaining the brush against the side of the forwardly moving car and moving the brush inwardly across the rear of the car when the rear corner of the car is reached.
Certain difficulties were experienced with the position switch in this apparatus, such switch employing a one way limit switch and a cam to trigger operation of the primary arm cylinder when the brush was contacted by a car. In order to avoid false triggering, and to permit proper resetting, the mechanism required fairly substantial movement of the cam before it would trigger, and as a result the triggering (i.e. commencement of operation) was not fast and positive. The slow triggering limited the speed of operation of the device and therefore limited the number of cars that could be processed through the apparatus.